Communications equipment and networks and methods of coupling signals therein are known. As this communications equipment has become smaller the desire for ever-smaller, more efficient, less complex, and less costly coupling networks and systems has grown. More recently more of this communications equipment has been tasked with operating in multiple frequency bands. For example cellular phones or devices or handsets now routinely operate in two or more distinct frequency bands, such as 800 or 900 MHz as well as 1.8 and above GHz.
It is known to provide multiple receiver front ends and multiple coupling networks to multiple mixers with each line up contributing its own frequency selectivity or filtering, however this is expensive in terms of cost and volume required within the equipment even when most or all of the respective components are integrated. One technique used for these multiple line ups includes a narrow band low noise amplifier transformer coupled to a mixer where the transformer is resonant with a capacitor for selectivity. It is known that resonating the transformer will provide filtering and using a varactor to tune this resonant frequency has been contemplated. However multiple lineups are required to cover multiple frequency bands.
Clearly a need exists for an integrated frequency selectable resonant coupling network and methods thereof suitable for use in integrated circuits adapted for communications equipment.